The Effect On Blood Brain Barrier Permeability During Carbon Monoxide Poisoning

Objective：Carbon monoxide (CO) is an colorless, tasteless, non-irritating gasformed as a by-product of burning organic compounds. The affinity of hemoglobin forCO is200to250times greater than affinity to oxygen. This results in competitive inhibition of oxygen release due to shift in the oxygen hemoglobin dissociation curve，reducing oxygen delivery and subsequent tissue hypoxia. Our bodies rely on oxygen tomaintain ell function and the normal function of the brain requires a lot of oxygen. Ca-rbon monoxide damage to body systems including brain damage are most vulnerable.Destination of our experiment is to establish rat model with acute carbon monoxidepoisoning.Blood brain barrier permeability was used by Evans blue method and brainwater contents was measured by dry-wet weigh method.The changes of brain watercontent and permeability of blood brain barrier were measured by the methods ofEvansblue(EB) fluorometry.AQP4expression was detected by immunohistochemical. Corr-elation between aquaporin4expression and the change of blood brain barrier aftercarbon monoxide poisoning in rats.Methods:1、84healthy Kunming male mouse,were divided into Air controlgroup,Carbon monoxide poisoning group,42mice in every group.Each group is dividedinto six sub-group.As follows:6h,24h,48h,72h,7d,14d,21d group,2mice in everygroup.Two brain was measured brain tissue water content,two measurements of braintissue permeability of EB,two perfusion the brain was done by immunohistochemicaldetection.2、Kunming male mouse were divided at random into two groups,air controlgroup and single injection one.99.9﹪CO was injected into both group intra-peritoneallyat a dosage of150ml/kg.3、Randomly tow male mouse were selected from each sub-group,model was successes for each sub-group corresponding point in time.Weighing10﹪chloral hydrate anesthesia was decapitated quickly and dislodged brain after carbon monoxide poisoning was injected.4、Randomly tow male mouse were selected fromeach sub-group.After the corresponding time points,10﹪chloral hydrate aldehyde wasinjected by3ml/kg.2﹪EB was injected though intravenous with2ml/kg.5minute wasfinished quickly.Changes in BBB permeability were determined by detection of EB.Curve was established by standard EB cuiqu liquid concentration.We can get braintissue EB efflux.5、The protein expression of AQP4was examined by immunohisto-chemical.We observed a lot of cells expressing and protein expression.Results:6h after carbon monoxide poisoning,water content of brain tissue and EBcontent increased,the protein expression of AQP4in contusion marginal region beganto crease. They reached summit at24h after operation,afterward dropped gradually,andstill maintained at the high level after72h （p＜0.05）.There was significantly positivecorrelation between protein expression of AQP4,the change of brain water content andchange of EB content.Conclusion: The change of AQP4protein expression are closely related to thedestruction of BBB and the formation and development of brain edema during the earlystage after traumatic brain injury.The early up-regulated expression of AQP4mayincrease permeability of blood brain barrier, which is concerned with the developmentof brain edema after the brain injury.